Sugary drinks linked to colorectal cancer in young women

11 May 2021 --- Sugar-sweetened beverages may boost the probability of developing colorectal cancer among women under 50, according to research by the Washington University School of Medicine.

Senior author Yin Cao, an associate professor of surgery and medicine at Washington University, says: “Colorectal cancer in younger adults remains relatively rare, but the fact that the rates have been increasing over the past three decades – and we don't understand why – is a major public health concern and a priority in cancer prevention.”

“In past work, we have shown that poor diet quality was associated with increased risk of early-onset colorectal cancer precursors, but we have not previously examined specific nutrients or foods,” she asserts.

Multiple servings linked with higher risk
Women who drank two or more servings of sugar-sweetened beverages per day were found to be twice as likely to develop early-onset colorectal cancer than those who drank one 8 oz serving per day.

The researchers found a 16 percent increase in risk for each 8 oz serving per day. From ages 13 to 18, an important time for growth and development, each daily serving was linked to a 32 percent increased risk of eventually developing colorectal cancer before age 50.

Additionally, the researchers found an association between sugar-sweetened drink intake and metabolic health problems such as type 2 diabetes as well as obesity. Countries like the UK are using taxes to help control added sugar in F&B products. 

Reducing sugar in beverages
This latest analysis used the Nurses’ Health Study II, which tracked the health of nearly 116,500 female nurses from 1991 to 2015. The participants answered surveys about diet, including the types and estimated amounts of beverages they drank. Of the total participants, over 41,000 also were asked to recall their beverage habits during their adolescence.

The researchers identified 109 diagnoses of early-onset colorectal cancer among the participants.

Cao states that despite the small number of cases, there is still a “strong signal” to suggest that sugar intake, especially in early life, is playing a role down the road in increasing adulthood colorectal cancer risk before age 50.

A switch to a healthier beverage?
While sugar-sweetened beverages were linked to an increased risk of early-onset colorectal cancer, some other drinks – including milk and coffee – were associated with a decreased risk. 

This observational study can’t demonstrate that drinking sugary beverages causes this type of cancer or that drinking milk or coffee is protective. Still, the researchers say that replacing sweetened beverages with unsweetened drinks, such as milk and coffee, is a better choice for long-term health. 

External experts also flag that more research needs to be done to draw firm conclusions, especially given that only 109 colorectal cancer cases occurred.

“Overall, these findings should be considered as preliminary and exploratory until larger studies are done in other populations, for example including men and women, and with a broader range of socioeconomic status, with varying dietary patterns),” says Dr. Carmen Piernas, who was not involved in the study. 

She is a university research lecturer and nutrition scientist at Nuffield Department of Primary Care Health Sciences, University of Oxford.Cao’s lab is funded by the National Cancer Institute and the National Comprehensive Cancer Network. 

The battle to reduce sugar
Previous studies revealed that taxes added to sugar beverages can lead to a decrease of their consumption. 

Rather than increase the price of drinks, the tax added to sugar products is designed to encourage manufacturers to reduce the amount of sugar in drinks. 

“Although the authors suggest the increase in bowel cancer may be linked to increased sugary drink consumption, this may not be quite the case in the UK,” flags Dr. Duane Mellor, who was also not involved with the study and is a registered dietitian and senior teaching fellow at Aston Medical School.

He points out that the introduction of the soft drink industry levy (SDIL) led to a reduction in sugar content of most soft drinks available in the UK.  

“Therefore, it will be interesting to see if these increases noted in the US are also happening in the UK over the next decade, to see if the theory that sugary drinks are associated with increased risk of bowel cancer continues to be seen following the introduction of the sugar tax.”

By Nicole Kerr